The leader of the group that launched the recent parcel bomb attacks
radicalised a generation of young Muslims during a “grand tour” of Britain,
it can be disclosed.

Anwar al-Awlaki was invited to speak to numerous groups around the country despite being a suspect in the September 11 attacks.

Security sources are concerned that Awlaki’s teachings became so widely acceptable that there are a number of Muslim disciples prepared to follow his advice and launch attacks in Britain.

In a glossy online magazine produced by al-Qaeda in the Arabian Peninsular,in July, Awlaki told his followers: "Assassinations, bombings, and acts of arson are all legitimate forms of revenge against a system that relishes the sacrilege of Islam in the name of freedom."

His disciples include Roshonara Choudhry, who was jailed for 15 years this week after trying to stab the MP Stephen Timms to death for his support of the Iraq war, and Umar Farouq Abdulmutallab, who tried to blow himself up on a flight to Detroit on Christmas Day using a bomb in his underpants.

Both were students at London University when they are thought to have met others who admired Awlaki.

Choudhry spent hours watching his videos on Youtube and told police: “Everybody listens to him and likes him.”

Awlaki was fleeing an FBI inquiry in the US in the wake of his involvement with three of the September 11 hijackers, when he arrived in Britain in late 2002.

But even with such a cloud hanging over him, he was “welcomed with open arms,” according to Alexander Meleagrou-Hitchens, an expert on Awlaki at the Centre for the Study of Radicalisation at King’s College, London.

“It would be no exaggeration to say that his reception was unprecedented – to this day almost no other foreign-based preacher has compared,” Mr Meleagrou-Hitchens said.

Awlaki lectured for the Muslim Association of Britain, the Federation of Student Islamic Societies (FOSIS), and the Islamic Forum Europe (IFE) based at East London Mosque.

He began a “grand tour” of Britain, from London to Aberdeen, as part of a campaign by the Muslim Association of Britain in which one lecture was held in conjunction with the London School of Economics, Imperial College, King’s College and the School of Oriental and African Studies – all part of the University of London.

He became a favourite speaker of a group called JIMAS and was a “distinguished guest” at the Federation of Student Islamic Societies annual conference at the University of Nottingham.

He was also a keynote speaker at the “ExpoIslamia” event held by the Islamic Forum Europe and appeared at an event at East London Mosque called “Stop Police Terror” in which he told his audience: “A Muslim is a brother of a Muslim, he does not oppress him, he does not betray him and he does not hand him over... You don't hand over a Muslim to the enemies.”

His views cannot have been a secret to many because he produced a lecture series on jihad in 2003 called “The Story of Ibn al-Akwa,” which was based on the Book of Jihad written by a 14th century scholar, Ibn Nuhaas.

It included headings such as “Jihad is the most beloved deed to Allah,” “The mujahid [holy warrior] is the greatest of all people” and “The pinnacle of Islam is jihad.”

While in Britain, Awlaki was also working on Constants in the Path of Jihad, which he produced in 2005, a few months after being banned from the country.

But it was only with the Fort Hood shootings in Texas, conducted by Major Nidal Hasan, a disciple of Awlaki, in November last year, that British Islamic organisations began to distance themselves from the preacher for the first time.

“The official line, from many prominent individuals and organisations, was that Awlaki’s radicalisation had been an insidious process that had caught them unawares,” Mr Meleagrou-Hitchens said.

But he said Awlaki’s views on violent jihad “would have been obvious to any regular consumer of his output.”